scholarly journals Air Flow Experiments on a Train Carriage—Towards Understanding the Risk of Airborne Transmission

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1267
Author(s):  
Huw Woodward ◽  
Shiwei Fan ◽  
Rajesh K. Bhagat ◽  
Maksim Dadonau ◽  
Megan Davies Wykes ◽  
...  
Keyword(s):  
Cross Sections ◽  
Aerosol Particles ◽  
Exhaled Breath ◽  
Proof Of Concept ◽  
Airborne Transmission ◽  
Size Fractions ◽  
Co2 Concentrations ◽  
Air Supply ◽  
Series Of Experiments ◽  
Flow Experiments

A series of experiments was undertaken on an intercity train carriage aimed at providing a “proof of concept” for three methods in improving our understanding of airflow behaviour and the accompanied dispersion of exhaled droplets. The methods used included the following: measuring CO2 concentrations as a proxy for exhaled breath, measuring the concentrations of different size fractions of aerosol particles released from a nebuliser, and visualising the flow patterns at cross-sections of the carriage by using a fog machine and lasers. Each experiment succeeded in providing practical insights into the risk of airborne transmission. For example, it was shown that the carriage is not well mixed over its length, however, it is likely to be well mixed along its height and width. A discussion of the suitability of the fresh air supply rates on UK train carriages is also provided, drawing on the CO2 concentrations measured during these experiments.

scholarly journals Experimental Investigation of Diffuser Hub Injection to Improve Centrifugal Compressor Stability

2005 ◽  
Vol 127 (1) ◽  
pp. 107-117 ◽  
Author(s):  
Gary J. Skoch
Keyword(s):  
Centrifugal Compressor ◽  
Surface Resistance ◽  
Flow Resistance ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Injection Rate ◽  
Flow Rates ◽  
Injection Flow ◽  
Air Supply ◽  
Series Of Experiments

Results from a series of experiments to investigate whether centrifugal compressor stability could be improved by injecting air through the diffuser hub surface are reported. The research was conducted in a 4:1 pressure ratio centrifugal compressor configured with a vane-island diffuser. Injector nozzles were located just upstream of the leading edge of the diffuser vanes. Nozzle orientations were set to produce injected streams angled at −8, 0, and +8 degrees relative to the vane mean camber line. Several injection flow rates were tested using both an external air supply and recirculation from the diffuser exit. Compressor flow range did not improve at any injection flow rate that was tested, and generally diminished as injection rate increased. Compressor flow range did improve slightly at zero injection due to the flow resistance created by injector openings on the hub surface. Resistance and flow range both increased as the injector orientation was turned toward radial. Leading edge loading and semivaneless space diffusion showed trends that are similar to those reported earlier from shroud surface experiments that did improve compressor range. Opposite trends are seen for hub injection cases where compressor flow range decreased. The hub injection data further explain the range improvement provided by shroud-side injection and suggest that stability factors cited in the discussion of shroud surface techniques are valid. The results also suggest that a different application of hub-side techniques may produce a range improvement in centrifugal compressors.

Pressure Effects of Foreign Gases on the 535.0 nm Fluorescence Line of Thallium

1985 ◽  
Vol 40 (8) ◽  
pp. 800-809 ◽  
Author(s):  
E. Lisicki ◽  
A. Bielski ◽  
J. Szudy ◽  
J. Wolnikowski
Keyword(s):  
Cross Sections ◽  
Pressure Effects ◽  
Pressure Broadening ◽  
Fluorescence Line ◽  
Series Of Experiments ◽  
The Cross ◽  
The Impact

Results of a series of experiments on pressure effects caused by various foreign gases on the 535.0 nm Tl fluorescence line emitted due to the photodissociation of TlI-molecules are summarized and some aspects of the Doppler and pressure broadening of this line are discussed. The impact broadening- and shift-cross sections are determined for two sets of mean relative velocities ū of the emitter-perturber pair. An attempt is made to analyse the cross-sections for different perturbers by investigating their dependence on the quantity (α/ū)2/5, where α is the polarizability of the perturber.

Experimental Investigations on Effect of Particles Removal in Cleanroom with Non-Unidirectional Airflow

2014 ◽  
Vol 580-583 ◽  
pp. 2428-2431
Author(s):  
Yu Wang
Keyword(s):  
High Performance ◽  
Particle Concentration ◽  
Frequency Converter ◽  
Local Area ◽  
Experimental Investigations ◽  
Contamination Control ◽  
Experimental Platform ◽  
Air Volume ◽  
Air Supply ◽  
Series Of Experiments

Efficient airflow delivery is key to achieve effective contamination control for a high-performance cleanroom. The influence of airflow organization on effect of particles removal in cleanroom with non-unidirectional airflow was investigated in this paper. A series of experiments were conducted on a cleanroom experimental platform with different airflow organization modes and supply air volume variation by frequency converter ( 40 to 50 Hz, 5Hz interval) on air-supply fan unit. The results showed that higher cleanliness could be gained at local area in cleanroom with radial airflow organization. Moreover, the outcomes from these experiments indicated that particle concentration at measuring points appeared more orderly when the cleanroom operated with radial airflow organization. The conclusion can be drawn that radial airflow can benefit contamination control at local area for cleanroom operation with non-unidirectional airflow when compared with ceiling-supply and wall-return airflow organization.

Study on the origin and collection of exogenous compounds in exhaled breath aerosol particles

2015 ◽  
Author(s):  
Göran Ljungkvist ◽  
Olof Beck ◽  
Karina Stein ◽  
Åsa Danielsson ◽  
Agneta Agge ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Exhaled Breath ◽  
Exogenous Compounds

scholarly journals Potential of Mass Spectrometry in Developing Clinical Laboratory Biomarkers of Nonvolatiles in Exhaled Breath

2016 ◽  
Vol 62 (1) ◽  
pp. 84-91 ◽  
Author(s):  
Olof Beck ◽  
Anna-Carin Olin ◽  
Ekaterina Mirgorodskaya
Keyword(s):  
Mass Spectrometry ◽  
Respiratory System ◽  
Progress Monitoring ◽  
Clinical Laboratory ◽  
Exhaled Breath Condensate ◽  
Aerosol Particles ◽  
Exhaled Breath ◽  
Protein Biomarkers ◽  
Abused Drugs ◽  
Potential Biomarkers

Abstract BACKGROUND Exhaled breath contains nonvolatile substances that are part of aerosol particles of submicrometer size. These particles are formed and exhaled as a result of normal breathing and contain material from distal airways of the respiratory system. Exhaled breath can be used to monitor biomarkers of both endogenous and exogenous origin and constitutes an attractive specimen for medical investigations. CONTENT This review summarizes the present status regarding potential biomarkers of nonvolatile compounds in exhaled breath. The field of exhaled breath condensate is briefly reviewed, together with more recent work on more selective collection procedures for exhaled particles. The relation of these particles to the surfactant in the terminal parts of the respiratory system is described. The literature on potential endogenous low molecular weight compounds as well as protein biomarkers is reviewed. The possibility to measure exposure to therapeutic and abused drugs is demonstrated. Finally, the potential future role and importance of mass spectrometry is discussed. SUMMARY Nonvolatile compounds exit the lung as aerosol particles that can be sampled easily and selectively. The clinical applications of potential biomarkers in exhaled breath comprise diagnosis of disease, monitoring of disease progress, monitoring of drug therapy, and toxicological investigations.

Electrically-Launched mm-sized Hypervelocity Projectiles

2019 ◽  
Author(s):  
W. Casey Uhlig ◽  
Paul R. Berning ◽  
Peter T. Bartkowski ◽  
Matthew J. Coppinger
Keyword(s):  
Transmission Lines ◽  
Hypervelocity Impact ◽  
Diameter Ratio ◽  
Outer Diameter ◽  
Proof Of Concept ◽  
Copper Anode ◽  
Mhd Simulations ◽  
Electromagnetic Launch ◽  
Series Of Experiments ◽  
Launch Systems

Abstract A series of experiments and simulations were performed as proof of concept that an electrically powered research gun could propel small cylindrical projectiles to hypervelocities. Although small-caliber electrothermal accelerators and other electromagnetic launch systems have been utilized for some years for laboratory hypervelocity impact and other studies [1-5], we developed a simple, reproducible device that allows impact studies and direct comparison to magnetohydrodynamic (MHD) simulations for design considerations, efficiency improvements, and validation studies. This work focusses on 4.8 mm cylindrical 7075-T6 aluminum projectiles with a length to diameter ratio of one (nominally a mass of 0.24 grams) and a 150-mm long, 25-mm outer-diameter 4043 steel barrel with a 4.8-mm diameter bore and 9.5-mm chamber that acts as the electrical cathode. The anode consists of a 6.3-mm diameter copper rod that is reduced to 2.9 mm then tapered to a point with the tip length over diameter ratio (L/D) varying from 2 to 5. The tip is placed at the chamber/bore junction. The copper anode is insulated by a polyethylene sleeve and epoxy surrounding the electrode such that the arc initiates only at the very tip. A 191 μF capacitor was used as the power source for all experiments. The applied voltage was varied from 10 kV to 20 kV, and the resulting inductance of the system varied from approximately 320 nH to 450 nH (due to varying separation in the copper transmission lines). Fits to the current pulse using an LRC circuit resulted in resistance on the order of 10 mΩ to 15 mΩ. Typically the portion of the electrical pulse responsible for the bulk of the acceleration of the projectile occurs within the first 15 μs; however, the projectile is accelerated during the entirety of the time it remains in the barrel, which is on the order of 40 μs to 50 μs.

scholarly journals Overview of aerosol properties associated with air masses sampled by the ATR-42 during the EUCAARI campaign (2008)

2013 ◽  
Vol 13 (9) ◽  
pp. 4877-4893 ◽  
Author(s):  
S. Crumeyrolle ◽  
A. Schwarzenboeck ◽  
J. C. Roger ◽  
K. Sellegri ◽  
J. F. Burkhart ◽  
...  
Keyword(s):  
Cross Sections ◽  
Aerosol Particles ◽  
Qualitative Evaluation ◽  
Cloud Microphysics ◽  
Air Masses ◽  
The North ◽  
Aerosol Mass ◽  
Aerosol Parameters ◽  
Scattering Cross Sections ◽  
Mass Concentrations

Abstract. Within the frame of the European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) project, the Météo-France aircraft ATR-42 performed 22 research flights over central Europe and the North Sea during the intensive observation period in May 2008. For the campaign, the ATR-42 was equipped to study the aerosol physical, chemical, hygroscopic and optical properties, as well as cloud microphysics. For the 22 research flights, retroplume analyses along the flight tracks were performed with FLEXPART in order to classify air masses into five sectors of origin, allowing for a qualitative evaluation of emission influence on the respective air parcel. This study shows that the extensive aerosol parameters (aerosol mass and number concentrations) show vertical decreasing gradients and in some air masses maximum mass concentrations (mainly organics) in an intermediate layer (1–3 km). The observed mass concentrations (in the boundary layer (BL): between 10 and 30 μg m−3; lower free troposphere (LFT): 0.8 and 14 μg m−3) are high especially in comparison with the 2015 European norms for PM2.5 (25 μg m−3) and with previous airborne studies performed over England (Morgan et al., 2009; McMeeking et al., 2012). Particle number size distributions show a larger fraction of particles in the accumulation size range in the LFT compared to BL. The chemical composition of submicron aerosol particles is dominated by organics in the BL, while ammonium sulphate dominates the submicron aerosols in the LFT, especially in the aerosol particles originated from north-eastern Europe (~ 80%), also experiencing nucleation events along the transport. As a consequence, first the particle CCN acting ability, shown by the CCN/CN ratio, and second the average values of the scattering cross sections of optically active particles (i.e. scattering coefficient divided by the optical active particle concentration) are increased in the LFT compared to BL.

scholarly journals Concept of Using 3D Printing for Production of Concrete–Plastic Columns with Unconventional Cross-Sections

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1565
Author(s):  
Jacek Katzer ◽  
Aneta Skoratko
Keyword(s):  
Cross Sections ◽  
Concrete Columns ◽  
Maximum Load ◽  
Fiber Reinforced Concrete ◽  
Plastic Behavior ◽  
Proof Of Concept ◽  
Ordinary Concrete ◽  
3D Printed ◽  
Future Direction

A concept of concrete–plastic columns was presented in the paper. As a proof of concept, a research program was conducted. Seven different cross-sections of columns formwork were 3D printed using plastic. The cross-sections represented three types of columns’ shapes: most common, rare, and impossible to be realized using traditional formworks (based on fractals). Prepared plastic formworks were filled with cement mortar playing the role of ordinary concrete. After 28 days of curing, the load–strain characteristics of all the concrete columns were tested. Achieved results were discussed. It was proven that concrete–plastic columns were characterized by quasi-plastic behavior while being ultimately destroyed. Columns with fractal-based cross-sections sustained the largest strains while maintaining a significant part of the maximum load. The achieved results proved that it is possible to completely omit traditional steel rebar-stirrup reinforcement. The future direction of needed research should cover larger columns and other concrete–plastic elements. Using fiber-reinforced concrete for the creation of concrete–plastic elements should be also tested.

scholarly journals Compression test of cold-formedsteel perforated profile with steel sheathing

Vestnik MGSU ◽  
2015 ◽  
pp. 43-52
Author(s):  
Aleksandr Yur’evich Shamanin
Keyword(s):  
Cross Sections ◽  
Oriented Strand Board ◽  
Axial Deformation ◽  
Plastic Properties ◽  
Steel Columns ◽  
Central Column ◽  
Series Of Experiments ◽  
The Stability ◽  
The Impact ◽  
Different Thickness

The subject of this paper is the stability and strength of cold-formed and perforated steel sigma-section columns with steel sheathing of different thickness. Ceilings with and without steel sheathing of different thickness are tested to failure in compression on a laboratory machine, which was based on a manual hydraulic jack. Series of 4 experiments with full-scale walls (2.5 m height) were carried out. Also, for examination of the role of boundary conditions, the sheet in a ceiling is either left free or connected to base with screws.In civil engineering there are many experiments and methodologies for calculating the strength and buckling of ceiling with the sheathing of various materials, such as oriented strand board and gypsum board. However, for producing superstructures of ships the materials with high plastic properties and strength characteristics are required. For example steel possesses such properties. It was the main reason for conducting a series of experiments and studying the behavior of cold-formed steel columns with steel sheathing. During the experiments the deformation of the cross-section of three equally spaced cross sections was determined, as well as the axial deformation of the central column in the ceiling with steel sheathing.The test results showed the influence of the thickness of sheathing and boundary condition of a sheet on the strength and buckling of ceiling. According to the results of the tests it is necessary to evaluate the impact of the sheathing made of different materials and if necessary to carry out further tests.

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